In recent years, in a lithography process in semiconductor manufacture, to achieve a high speed and high integration of an integrated circuit, a technology using ultraviolet rays (KrF, ArF, or F2 laser) in an exposure process has been developed. In recent years, a technology using EUV light (extreme ultraviolet light) with a shorter wavelength has been developed, but an apparatus using EUV light has a problem of high apparatus cost and others.
Moreover, in the conventional electron beam exposure technology used for micro-patterning so far, long-time exposure is required. For this reason, under the present circumstances, the electron beam exposure technology is used only for prototyping a small number of semiconductors for a special use purpose, posing a problem such that this technology cannot be applied to mass production of semiconductors.
As a method of solving both of these problems (apparatus cost and throughput), a nano imprint technology has attracted attention, in which a minute convexo-concave pattern in a nano size is formed on a substrate by using a polymer as a material to manufacture a high-functionality device such as a semiconductor, a recording medium, or an optical element.
A nano imprint scheme is a method of pressing a substrate coated with a resist (a resin material) onto a mold (a form) having a minute convexo-concave pattern formed thereon by electron beam exposure to transfer the minute convexo-concave pattern of the mold to a resist layer.
The nano imprint technology has features such that apparatus cost by microfabrication is inexpensive compared with the EUV scheme or the like and minute convexo-concave pattern shape in a size of several tens of nanometers can be transferred.
However, the nano imprint technology has a faulty peel problem in which when the resist layer and the mold are peeled after a minute convexo-concave pattern is transferred to the resist layer on the substrate, the minute convexo-concave pattern transferred to the resist layer tends to be damaged. This is because the nano imprint technology includes a transferring process of bringing the mold and the resist layer into contact with each other to form a minute convexo-concave pattern, and the faulty peel problem is a fundamental problem unavoidable due to the transferring process mentioned above.
Several measures have been suggested so far to mitigate this faulty peel problem. For example, PTL 1 discloses a pattern forming method in which an angle formed between a direction of a line of a convexo-concave pattern and a mold peeling direction is adjusted to prevent the convexo-concave pattern from being damaged at the time of peeling.
Also, PTL 2 describes a method of forming a sufficient deformation adjacently to the mold so as to produce a resilient force larger than a bonding force between an imprinting material and the mold. This is thought to improve an imprinting method for use in a contact lithography process.
Furthermore, PTL 3 discloses a device manufacturing method in which, with the mold and the resin being in contact with each other, a state from the time when the mold starts moving in a direction of going away from the resin to the time of peeling is divided into a first state and a second state and a load change ratio acted between the mold and resin in the second state is set smaller than that in the first state. With this, it is thought to be able to achieve a high-speed releasing process and an excellent throughput.